Different valve types are known for assembly in pipelines. In general, the existing systems and devices are usually applications with little involvement as regard to pressures, temperatures, and fluids. Besides, the complexity of their operation requires specialized staff, not only for their installation, but for their operation as well.
It is known the system disclosed by the patent document U.S. Pat. No. 6,041,806 can only be applied to soft pipelines made of materials such as plastic, PVC, lead, polyethylene, etc., due to that fact that conceptually, the ball cuts the pipe with one of its edges, upon rotating the valve stem, and this is only possible in pipes made of soft materials.
In addition, this system is limited to low pressures, of about 2 to 5 bars and, to pipelines that, in some way, are underground or in walls. This is due to the fact that the axial force caused by the pressure, cannot be sustained safely by the adjustment of the split body with rubber seals. Thus, and even though this is acceptable in water, it is not recommended in gas or other applications, and even less in refineries and the chemical or petrochemical industry in general.
Besides, the seal of the ball with o-rings within the body of the valve is not effective as the cutting edge of the ball (which is used to cut the pipe) tends to engage the o-ring, generating its later breaking.
It can also be observed that due to the design of the stem that moves the ball, the stem can be expelled by the pressure.
The patent document U.S. Pat. No. 5,620,020 discloses a device designed to work in plumbing tasks, as its sealing system is very precarious. This is due to the fact that there is not a good adjustment of the seal to the body that is inserted upwards. In addition, the shears type cutting is not very good, so imperfections may affect the seal.
In this manner, the above mentioned device is exclusively limited to plumbing tasks which utilize soft pipes, like those made of plastic, lead and eventually, in some cases, a material of the type called hydrobronz. Axial forces, due to the pressures on the pipelines, may be high, and this system does not have a solution for this because the adjustment of the split body with rubber seals on the pipe is not safe.
As it may be observed in FIGS. 1, 2, 3, 4 and 5, its inefficiency if applied to medium and high pressures is clearly evident, particularly with fluids having certain risk, such as fuel or toxic gases, and in cases of pipelines made of steel, cast, stainless, etc. Besides, seats of o-ring type are not displaceable or suitable because they are elastic and there are chances of breaking upon turning the ball.
Even though displaceable seats are disclosed in other patent documents, such as U.S. Pat. Nos. 0,587,108, 2,396,964, 3,665,953, 4,527,586, and U.S. Pat. No. 5,063,957, none of them utilizes split tightness joints with extensions for transverse sealing.
In addition, the above mentioned documents show devices that are only useful for underground pipelines, where axial forces, once the pipe is cut, are supported by the same soil covering the pipe.